The fast-diffusion process was investigated in a molecular dynamics study of the superionic phase. The calculated concentration of cationic Frenkel-pairs was in good agreement with experimental data. A few of these defects were dissociated and contributed to diffusion, whereas the major part quickly recombined. Analysis of the cation trajectories permitted the identification of 3 types of discrete jump; characterised by their length. The nearest-neighbour jumps were dominant and followed 2 different migration paths. A quantitative analysis, including the calculation of the atomic jump frequencies, was carried out. The cations spent most of their time on normal lattice sites. The combination of the various jumps resulted in a complex migration mechanism, and the corresponding effective activation enthalpy was determined. All of the results provided an extended view of the atomic diffusion process in a superionic conductor.

Complex Atomic-Diffusion Mechanism in Ionic Superconductors - the Case of the Lithium-Oxide Antifluorite. M.Hayoun, M.Meyer, A.Denieport: Acta Materialia, 2005, 53[10], 2867-74